Synergistic herbicidal composition comprisng N-(butoxymethyl)-6&#39;-tert-butyl-2-chloro-o-acetotoluidide and diallate

ABSTRACT

A synergistic herbicidal composition comprising as the active ingredient a mixture of N-(butoxymethyl)-6&#39;-tert-butyl-2-chloro-o-acetotoluidide and S-(2,3-dichloroallyl) N,N-diisopropylthiocarbamate and use of said composition particularly in sugarbeets and in cereal crops, e.g., wheat and barley.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention herein pertains to the field of herbicides. In particular,the invention pertains to a synergistic herbicidal composition having asthe active ingredient a mixture ofN-(butoxymethyl)-6'-tert-butyl-2-chloro-o-acetotoluidide andS-(2,3-dichloroallyl) N,N-diisopropylthiocarbamate (common name"diallate"). The herbicidal composition herein has particularapplication in the control of undesired plants associated withsugarbeets and cereal crops, e.g., wheat and barley.

2. Description of the Prior Art

It is known in the prior art to use various carbamates orthiolcarbamates as herbicides, either individually or in combinationwith various other herbicidal compounds. In such carbamate compounds,the nitrogen substituents and ester moieties are commonly phenyl,benzyl, alkyl or alkenyl groups which may be substituted with halogen oralkoxy groups, but other groups may also be used.

The particular thiocarbamate of interest herein and use as a componentof the combination herbicide of the present invention, i.e.,S-(2,3-dichloroallyl) N,N-diisopropylthiocarbamate ("diallate"hereinafter for brevity), is a known compound having herbicidal use. Thepreparation of diallate, herbicidal compositions containing same and usethereof are covered in U.S. Pat. Nos. 3,167,571, 3,330,821 and3,330,643. In addition, diallate is the active ingredient in MonsantoCompany's commercial Avadex herbicide; "Avadex" is a registeredtrademark of that company.

A variety of chemical compounds have been admixed with various membersof the above-mentioned carbamates in efforts to discover new herbicidalcompositions having unique additive, antagonistic or synergisticproperties with respect to different weed plants associated with variouscrop plants. Illustrative of prior art herbicide mixtures containingcarbamates and other herbicidal compounds are those containing variousaryl alkyl ureas such as fenuron (1,1-dimethyl-3-phenylurea), monuron(1,1-dimethyl-3-p-chlorophenylurea), diuron(1,1-dimethyl-3-(3,4-dichlorophenylurea), neburon[3-(3,4-dichlorophenyl)-1-n-butyl-1-methylurea], or similar ureaswherein the nitrogen or phenyl groups are substituted with a methoxyradical (U.S. Pat. No. 3,095,299 and Belgian Pat. No. 819,097). Othercarbamate herbicide mixtures contain 1-phenyl-4-amino-5-chloropyridazine(Belgian Pat. No. 810,793); or a 4,4'-bipyridylium quaternary salt(Japanese Pat. No. 7204000); or 3,4-dichloropropionanilide (JapanesePat. No. 7301486); or 2,4-D and/or MCPA (British Pat. No. 1301613); orpentachlorophenol or a salt thereof (Japanese Pat. No. 7102520).Diallate is the thiocarbamate component in the above Belgian Pat. No.810,793.

It is also known in the prior art to use various2-halo-2',6'-dialkyl-N-(alkoxyalkyl) acetanilides as herbicides eitherindividually or in combination with other herbicidal compounds. Forexample, U.S. Pat. No. 3,551,132 discloses the herbicidal use of2-chloro-2',6'-diethyl-N-(methoxymethyl) acetanilide (common namealachlor) admixed with 3'-(carbamoyloxy) anilides. British Pat. No.1,176,547 discloses the herbicidal use of a mixture of alachlor andlinuron, i.e., 3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea. U.S. Pat.Nos. 3,442,945 and 3,547,620 disclose a broad class of herbicidal2-halo-2',6'-dialkyl-N-(alkoxyalkyl) acetanilides, expressly includingN-(butoxymethyl)-6'-tert-butyl-2-chloro-o-acetotoluidide; this compoundhas tentatively been designated as "terbuchlor"; (an application byapplicant's assignee is pending before the American Standards Institutefor registration of this name as the common name for said compound).Hence, the term "terbuchlor" will sometimes be used hereafter in thespecification for brevity.

To applicant's knowledge, there has been no recognition or disclosure inthe prior art of a herbicidal composition comprising terbuchlor and athiocarbamate, in particular diallate, which together impartcomplementary, supplementary and/or synergistic action with respect,particularly, to undesirable vegetation associated with sugarbeets andcereal crops, such as wheat and barley.

The phenomenon of synergism is well known to those skilled in the artand, in the herbicidal art, relates to herbicidal compositions of mixedcomponents whose total herbicidal effect is unexpectedly greater thanthe additive effect of the individual components on particular plants ora spectrum of plants. The use of synergistic mixtures for the control ofplant growth permits the utilization of a lesser total amount ofherbicidal composition and/or lesser quantities of individual componentsin the composition to obtain the same or improved results than areobtained when a greater amount of herbicidal composition containing onlythe individual components or additive mixtures thereof. The use oflesser quantities of active ingredients in a herbicidal composition mayalso increase the margin of crop safety in the use of those activeingredients.

The concepts of synergism and antagonism (i.e., negative, neutralizingor nullifying effect of one component on another component) inherbicidal combinations have been reduced to mathematical formulationand graphical representation by some authors. For example, by the methoddescribed by S. R. Colby in "Weeds," Volume 15, No. 1 (1967) pages20-22, the expected response of a combination of herbicides is obtainedby taking the product of the percent-of-control values for theindividual herbicides and dividing by (100)^(n-1) where n is the numberof herbicides in the combination.

Another method of expressing synergism and antagonism is described by P.M. L. Tammes in "Netherlands Journal of Plant Pathology", 70 (1964),73-80. By the Tammes method, a graphic representation is given of theeffect of mixtures of herbicides. Each of the components is expressed asa coordinate on a graph and a quantitatively defined effect, e.g., apercent plant mortality, e.g., 50%, 85%, etc., is inserted in the graph.These values are obtained by interpolation. The line which connects thepoints is called an "isobole." With an isobole the effect of differentproportions of the individual components can be evaluated. The Tammesisoboles method has proven reliable in evaluating the synergistic effectof the herbicidal composition of this invention.

As used herein the term "active ingredient" denotes a mixture ofterbuchlor and diallate having the combined supplementary, complementaryand synergistic properties unique to this mixture.

The term "plant" as used herein encompasses dormant seeds, germinantseeds, germinative seeds, emerging seedlings and established vegetationincluding roots and above-ground portions.

The term "control" as used herein is inclusive of the effects ofkilling, inhibiting the growth, reproduction or proliferation andremoving, destroying or otherwise diminishing the occurrence or activityof plants and is applicable to any of the stated effects or combinationsthereof.

SUMMARY OF THE INVENTION

The present invention relates to a synergistic herbicidal compositioncontaining as the active ingredient therein a mixture of terbuchlor anddiallate as above defined, and to the herbicidal use of suchcompositions particularly useful in cereal crops, e.g., wheat andbarley, and in sugarbeets, to control undesired plants such as Galiumaparine and Chenopodium album.

DESCRIPTION OF PREFERRED EMBODIMENTS Example

Terbuchlor may be prepared by methods generally known to the art. Forexample, in Example 4 of each of the above-cited U.S. Pat. Nos.3,442,945 and 3,547,620, terbuchlor is prepared by reacting2-tert-butyl-6-methyl-N-methyleneaniline and chloroacetyl chloride withn-butanol according to conditions noted in the example.

Diallate also may be prepared by known methods commonly used to preparethiocarbamates. See the above-cited U.S. Pat. Nos. 3,167,571, 3,330,821and 3,330,643. As disclosed, e.g., in U.S. Pat. No. 3,330,821, severalmethods are available for the preparation of thiocarbamate esters. Forexample, in one method the halide corresponding to the desired ester iscondensed with an alkali metal thiocarbamate. The alkali metalthiocarbamates are prepared by the reaction of carbonoxysulfide withamines in the presence of alkali. In another method, a thionocarbamateester is rearranged to a thiol ester by reaction with an alkyl halide;the rearrangement being accompanied by transesterification. Yet anothermethod for the preparation of thiolcarbamates is to condense a carbonylhalide with a mercaptan or mercaptide.

Terbuchlor and diallate were applied as a tank mix and incorporated intoa cover layer of a sandy loam soil contained in plastic pots andpreviously sown with crop and weed seeds at 1 cm depth. Application ofthe mixed herbicide was made at a volume equivalent of 4000 l/ha with aDevilbiss atomizer No. 152. Initial irrigation of 1 mm was applied byoverhead means and subsequent watering requirements by subirrigation.The plants were visually observed approximately three weeks after sowingand the results recorded.

The synergistic response for terbuchlor/diallate herbicidal mixtures iswell shown by data in Tables 1 and 2. The average rates of the threeherbicides, i.e., terbuchlor, diallate and a mixture of the two,required to control 85% of the weeds (GR₈₅), and the average maximumrates of the herbicides for 15% or less growth reduction (GR₁₅) of thecrop plants is shown for illustrative purposes.

A Tammes isobole graphic representation of the synergistic effect ofterbuchlor/diallate combinations shows on a coordinate graph theconcentration in kg/ha required to achieve GR₈₅, for example, withdiallate rates shown along the ordinate (horizontal axis) and terbuchlorrates shown along the abscissa (vertical axis). A line is then drawn tojoin the GR₈₅ rates for each compound; this line is the additive isobolefor the mixture. Then holding one of the component rates constant whilevarying the rate of the other component, data points for each GR₈₅ rateare fixed on the graph. Any combination of weight ratios of thecomponents falling inside (or under) the additive isobole and having aGR₈₅ rate for weeds should exhibit synergism, and the correspondinginterpolated curve is termed the synergistic isobole. Combinations whoseGR₈₅ data points fall outside (or above) the additive isobole shouldexhibit antagonism and the corresponding interpolated curve is termedthe antagonistic isobole. Data points falling on the additive isoboleline itself represent mixtures whose combined components have onlyadditive effects. If a particular herbicidal combination has a GR₈₅ ratefor weeds within the area under the additive isobole for thatcombination, but the data also exhibits injury to the crop greater than15% at that rate, obviously, the herbicidal combination may not beselective for use in that particular crop under the specific testconditions.

In a specific application of the Tammes isoboles method, data tabulatedin FIGS. 1 and 2 show the application rates (in kg/ha) for theindividual components terbuchlor and diallate and various concentrationratios of each in mixtures thereof required to achieve GR₈₅ for thespecific weeds Galium aparine and Chenopodium album, respectively, inwheat, barley and sugarbeets. Data points for the GR₈₅ rates are fixedon the graph below the additive isobole and a line of best fit is drawnthrough the data points to derive a curve termed the "interpolativesynergistic isobole."

The active ingredient herein can be admixed with one or more adjuvantswhich can be solid or liquid extenders, carriers, diluents, conditioningagents and the like to form herbicidal compositions. Herbicidalcompositions containing the active ingredients of this invention can beformulated with or in the form of granules, wettable powders, aqueoussuspensions, dust formulations, emulsifiable oils and solutions insolvents. In general, these formulations can all contain one or moresurface-active agents.

Surface-active agents which can be used in herbicidal formulation arewell known to those skilled in the art and have been well documented inpatents, bulletins and textbooks.

The preparation, formulations and particle size of the granules,wettable powders, aqueous suspensions, dusts, emulsifiable oils andsolutions in solvents are also well known to those skilled in the artand well documented.

The active ingredient is usually present in the herbicidal compositionsin a range of about 0.5 to 95 parts by weight per 100 parts by weight ofwettable powder and dust formulations and from about 5 to 95 parts byweight per 100 parts by weight emulsifiable oil formulations.Formulations containing more or less than the above quantities of activeingredient can easily be prepared by those skilled in the art.

The quantity of active ingredient to be used in the field may varywithin certain limits depending upon variables known to those in theart, e.g., condition of the soil, climate, plants, etc. In general,however, amounts ranging from about 0.05 to 6.0 or more kg/ha should beadequate; a preferred range being from about 0.125 to 4.0 kg/ha orsuitably, an amount within the range of from 0.250 to 2.0 kg/ha.Terbuchlor/diallate ratios may vary within fairly wide limits, e.g.,from 1:8 to 8:1, a preferred ratio being within the range of from 1:4 to4:1 or even 1:2 to 2:1.

Modes of application of the herbicidal compositions of this invention tothe plant are well-known to those skilled in the art. The application ofliquid and particulate solid herbicidal formulations to the above-groundportions of plants can be carried out by conventional methods, e.g.,power dusters, boom and hand sprayers and spray dusters. Although inmore practical and recommended usage, the herbicidal compositions hereinshould be applied simultaneously as conjugate components in a mixture.However, it is within the purview of this invention to apply theindividual components sequentially in either order, the time intervalbetween successive applications being such as to accomplish the objectof this invention, i.e., the supplementary/complementary/synergisticeffects of terbuchlor/diallate combination.

While the illustrative embodiments of the invention have been describedherein before with particularity, it will be understood that variousother modifications will be apparent to and can readily be made by thoseskilled in the art without departing from the scope and spirit of theinvention. Accordingly, it is not intended that the scope of the claimsappended hereto be limited to the examples and description set forthherein but rather the claims be construed as encompassing all thefeatures of patentable novelty which reside in the present inventionincluding all features which would be treated as equivalents thereof bythose skilled in the art to which the invention pertains.

I claim:
 1. A herbicidal composition consisting essentially of aherbicidally effective amount of a mixture of (a)N-(butoxymethyl)-6'-tert-butyl-2-chloro-o-acetotoluidide and (b)S-(2,3-dichloroallyl) N,N-diisopropylthiocarbamate wherein the ratio ofa to b is within the range of from about 1:8 to 8:1.
 2. A herbicidalcomposition consisting essentially of a herbicidally effective amount ofa mixture of (a)N-(butoxymethyl)-6'-tert-butyl-2-chloro-o-acetotoluidide and (b)S-(2,3-dichloroallyl) N,N-diisopropylthiocarbamate wherein the ratio ofa to be is within the range of from about 1:4 to 4:1.